The present invention is directed generally to fiber optical communications and more particularly to a configuration for pumping a Raman fiber amplifier.
Fiber Raman amplifiers are useful devices for providing gain to optical communications signals that propagate along optical fibers. One of the advantages of Raman amplifiers is that the gain is distributed over a long length of fiber, typically several kilometers, thus increasing the signal to noise ratio. The fiber Raman amplifier is pumped with high levels of pump light, typically around several hundred milliwatts and above. This contrasts with the optical communications signals, that are typically at the level of around a few millliwatts. The higher levels of Raman pump light result in greater demands on the power handling capabilities of the components through which the pump light passes.
Generally, the present invention relates to an approach for incorporating a Raman amplifier pump unit in a fiber equipment rack. The approach reduces the number of connectorized components that the pump light passes through, thus reducing the possibility of damaging fiber connections by passing the high power Raman pump light through fiber connections. The approach also reduces the possibility of an operator being inadvertently exposed to the high power Raman pump light, thus increasing operator safety.
One particular embodiment of the invention is directed to an optical communications station. The station includes a fiber communications link carrying a fiber communications signal falling in a signal wavelength range and a fiber equipment rack having fiber equipment units for communicating with the fiber communications link. The fiber equipment units include a Raman pump unit generating Raman pump light in a pump light wavelength range. A fiber interface frame contains fiber interface devices for interfacing between the fiber communications link and the fiber equipment rack. A coupling unit is disposed between the fiber communications link and the fiber interface devices to permit passage of light in the signal wavelength range between the fiber communications link and the fiber interface devices and to couple the Raman pump light from the Raman pump unit into the fiber communications link. The fiber communications link provides Raman gain to the fiber communications signal.
Another embodiment of the invention is directed to a method of operating a fiber communications station. Optical communications signals are propagated between a fiber communications link and a fiber communications equipment rack via a set of fiber interfaces. Signals are generated in the fiber communications equipment rack for controlling a Raman pump unit. Raman pump light is injected from the Raman pump unit into the fiber communications link while bypassing the set of fiber interfaces.
Another embodiment of the invention is directed to an optical station having means for propagating optical communications signals between a fiber communications link and a fiber communications equipment rack via a set of fiber interfaces, means for generating signals in the fiber communications equipment rack for controlling a Raman pump unit, and means for injecting Raman pump light from the Raman pump unit into the fiber communications link while bypassing the set of fiber interfaces.
Another embodiment of the invention is directed to an optical communications system that includes an optical transmitter producing optical communications signals in a signal wavelength range, a fiber communications link coupled to receive the optical communications signals, and an optical receiver receiving at least a portion of the optical communications signals from the fiber communications link. At least one of the optical transmitter and the optical receiver includes a fiber equipment rack having fiber equipment units for communicating with the fiber communications link. The fiber equipment units include a Raman pump unit generating Raman pump light in a pump light wavelength range. A fiber interface frame contains fiber interface devices for interfacing between the fiber communications link and the fiber equipment rack. A coupling unit is disposed between the fiber communications link and the fiber interface devices. The coupling unit permits passage of light in the signal wavelength range between the fiber communications link and the fiber interface devices. The coupling unit couples the Raman pump light from the Raman pump unit into the fiber communications link, whereby the fiber communications link provides Raman gain to the fiber communications signal.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify these embodiments.